Radio frequency identification (RFID) systems are used in a variety of applications, ranging from warehouse inventory control and container tracking, through automatic toll payment, to automatic supermarket cashier applications. In a typical RFID system, an RF transponder is attached to, or incorporated into, a tracked object. RF transmissions between an interrogation device or a reader and the transponder are used for identifying or controlling the object, reading data, writing data or otherwise communicating with the transponder.